A tourniquet is a medical device designed to compress an artery in a limb (arm or leg) to completely stop the flow of blood beyond the application point. Its purpose is to control catastrophic, life-threatening external hemorrhage that cannot be stopped by less invasive means. While often seen as a tool of last resort, prompt application is a life-saving intervention when faced with uncontrollable bleeding.
Identifying When a Tourniquet is Necessary
Tourniquets are reserved for severe bleeding from a limb that poses an immediate threat to life, where blood loss could lead to death within minutes. The primary indicator is bleeding that is profuse or uncontrollable, often characterized by bright red blood that is spurting or pulsating from the wound. This visual evidence suggests a major arterial or venous injury requiring immediate and definitive action.
Direct pressure is the first and simplest intervention for a wound. If direct pressure with a clean cloth or gauze fails to stop the bleeding, or if the dressing quickly becomes saturated with blood, a tourniquet becomes necessary.
There are also specific traumatic scenarios that justify immediate tourniquet use without first attempting direct pressure. These include a traumatic amputation or a severely mangled extremity where a major vessel is obviously compromised. Tourniquets are also warranted in mass casualty incidents or situations where the scene is unsafe, making it impossible for a rescuer to safely maintain continuous direct pressure on the wound.
The device is exclusively for injuries on the arms and legs, as it is impossible to effectively apply the necessary pressure to stop blood flow on the torso, neck, or head. The prompt use of a tourniquet in these life-threatening situations is meant to buy time until the patient can receive advanced medical care.
Proper Application and Technique
Commercially manufactured tourniquets utilize a windlass rod mechanism to achieve the necessary arterial occlusion. While improvised devices can be used in an absolute emergency, they are significantly less effective and may cause greater tissue damage due to their narrow surface area.
Application begins by placing the tourniquet high on the injured limb, approximately two to three inches above the wound and closer to the torso. It is important to avoid placing the device directly over a joint, such as the elbow or knee, because the bone structure in these areas prevents the tourniquet from effectively compressing the artery. The device can be applied over clothing, but placement directly on the skin is preferable if possible.
The strap must first be pulled through the buckle as tightly as possible to remove all slack before engaging the windlass. The windlass rod is then twisted repeatedly until the bleeding from the wound completely stops. This is the visual confirmation of effectiveness; if the bleeding only slows down, the tourniquet is not tight enough and requires further tightening.
Once the bleeding is fully controlled, the windlass rod must be secured into its clip or locking mechanism to prevent it from unwinding. A successful application will also result in the absence of a pulse below the tourniquet. Immediately after securing the device, the time of application must be clearly marked on the tourniquet itself or on the patient’s forehead.
Safety Protocols and Common Misconceptions
A major misconception is that applying a tourniquet automatically results in the loss of the limb. Modern trauma data shows that the risk of death from uncontrolled bleeding vastly outweighs the risk of permanent limb damage when the device is used correctly. Studies have demonstrated that if a tourniquet is applied for less than two hours, the risk of permanent injury is extremely low.
The general safety window for continuous application is widely considered to be up to two hours, with the likelihood of nerve or muscle injury increasing beyond that time. Muscle damage begins to occur after this two-hour threshold, though amputation is typically only required if application extends for many hours. This time limit underscores the necessity of transporting the patient to advanced medical care as quickly as possible once the tourniquet is applied.
A secondary misconception is the practice of loosening a tourniquet periodically to “let blood flow back” to the limb. Once a tourniquet is applied and the bleeding is controlled, it must not be loosened or removed by an untrained rescuer. Loosening the device can restart the hemorrhage, potentially causing the patient to bleed to death or introducing metabolic waste products back into the circulation.
Documentation of the application time is a non-negotiable safety protocol because it informs the receiving medical team about the duration of ischemia. For any bleeding that is not life-threatening, or for wounds located on the torso, neck, or head, the tourniquet is inappropriate, and continuous direct pressure remains the standard of care.